Reliable and efficient fluid pressurizing devices, such as centrifugal compressors, have been developed and are often utilized in a myriad of industrial processes (e.g., petroleum refineries, offshore oil production platforms, and subsea process control systems). In these devices, undesirably high levels of noise may be generated. For example, in a centrifugal compressor, process fluids may flow through the regions of the impeller outlet and the diffuser inlet at velocities sufficient to generate the high levels of noise. The noise generated may often have a frequency band in a frequency range that human ears may be sensitive to; and thus, may create an undesirable working environment for nearby operators. In addition to presenting a nuisance to the nearby operators, the noise may also result in unintended vibrations and structural damage of the compressors and/or components thereof.
In view of the foregoing, the compressors may often incorporate noise attenuators to reduce the high levels of noise. For example, external attenuators or devices, such as enclosures and wraps, may often be utilized to reduce the high levels of noise. Utilizing the external devices, however, often leads to increased overall cost as the external devices are often provided as an add-on for the already manufactured compressors. Further, the external devices reduce the high levels of noise by insulating structural components of the compressor, and not by reducing the generation and/or excitation of sound waves traversing along or through fluid passages of the compressors. Due to the limitations of the external devices, internal devices, such as acoustic liners or resonators, have been developed and are often disposed adjacent diffuser channels of the compressors to attenuate the noise generated by the process fluids. The acoustic liners may attenuate the high levels of noise by exploiting the Helmholtz resonance principle. For example, the sound waves generated by the process fluids may oscillate through perforations and/or cells formed in the acoustic resonator fluidly coupled with the diffuser channels. The oscillation of the sound waves via the cells may dissipate the acoustic energy and thereby attenuate the noise. The acoustic resonator may also attenuate the noise by providing a local impedance mismatch to reflect the acoustic energy upstream. While the acoustic liners may provide a viable option for attenuating the noise, current designs and/or methods implement acoustic resonators that are “pre-tuned” to attenuate a desired noise frequency, and it is not possible to vary the “pre-tuned” the noise frequency during operation of the compressor. In order to change the “pre-tuned” frequency, the acoustic resonator may need to be removed from the compressor and tuned to the new desired frequency. This may be a time consuming and costly process.
What is needed, then, is an improved system for integrating acoustic resonators in fluid pressurizing devices, such that desired noise frequency to be attenuated may be varied during operation of the fluid pressurizing devices.